My 5 Favorite “Which One Doesn’t Belong” Images

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submitted by
Laura Wagenman
MCTM Communication Committee Chair

Narrowing down to just 5 favorite Which One Doesn’t Belong images was difficult. Not only are there a wealth of resources on the site, following @WODBMath and #wodb on Twitter, and this Google folder expands your options to even more treasures.

The website was created by Mary Bourassa, @MaryBourassa, inspired by the “Math Twitter Blog-o-Sphere”, otherwise known as MTBOS. According to the website, this is a “website dedicated to providing thought-provoking puzzles for math teachers and students alike. There are no answers provided as there are many different, correct ways of choosing which one doesn’t belong. Enjoy!”

There are many ways to use these images in a classroom. I had students write reasons for which didn’t belong by themselves then they shared with a partner. We then discussed whole group. The Teaching Channel has wonderful videos by grade level of how to implement as well.

My Favorites

1. Teaching 5th grade, this was a great way to find out what my students knew about fractions. It gave me a starting place to see if students saw benchmarks of ¼, ½, ¾, and a whole. I also found if students were familiar with equivalent fractions and decimal equivalents.

2. I initially used this with my class to get a glimpse into my students’ background knowledge with telling time on an analog clock. It was so exciting to hear students relate the images to angles, fractions, and decimals.

3. The responses to this image were eye opening. My initial thought was this would bring a discussion of factors, odd and even, and possibly a discussion about square roots. What I found was there were students who still had gaps in place value, calling the 16, a 1 and a 6. I was then able to plan instruction to fill those gaps in learning.

4. I usually start the year with this image as all students can share justifications because of the different colors. Vocabulary such as vertices, angle measures, description by side lengths, and symmetry provide rich conversations.

5. This is one of my favorites because it elicits such creative responses. Students have to think deeply to find mathematical justification with objects that don’t at first appear to be mathematical.